While there are traditional caches nearby, this is an earthcache. There is no physical cache at this location. See below for logging requirements. The posted coordinates will take you to the northwest corner of Umatilla Landing Park.
Rivers are a powerful force in shaping the land. They are one of the erosional agents that breaks apart rocks and one of the main transporter of these rocks (known as sediments). The size of the sediment that is transported is heavily dependent on the speed of the water body. Water in faster rivers has more force behind it, with slower rivers transporting smaller sizes. The sediment content of a river or stream is known as its load.
As the speed of the water slows down, the river will deposit portions of its load, beginning with the largest rocks. Where a river or stream enters a larger body of water with a lower speed, the originating river will sometimes deposit large portions of its load to form a river delta. Good examples of river deltas include the mouth of the Mississippi River in Louisiana and the mouth of the Yakima River in Richland.
There are other factors behind the formation of deltas. The Columbia River, for example, does not have a delta where it enters the Pacific Ocean at Astoria. This is because the ocean current redistributes the Columbia's load, creating such features as Long Beach in Washington. While the Columbia distributes large amounts of sediment into the Pacific Ocean, it's not enough to create a delta before it can be swept away.
The size of a river itself compared to the body of water it flows into is also a contributing factor into whether it forms a river delta or not, because the bigger a river is the more sediment it can carry. River deltas are typically sandy areas that the incoming river has to flow through to make it into the new body of water.
To log this earthcache, you will need to send me the answers to the following questions:
Questions:
Does the Umatilla River create a river delta where it enters the Columbia River?
- If yes, what do you observe about the size of the delta?
- If no, what factors are making it so that a delta cannot form?
If trees obscure your view, there is a narrow sidewalk on the bridge carrying 730 over the Umatilla River. Please be safe and watch your kids!